Personal mobile devices have become increasingly popular. Users typically carry multiple personal mobile devices at any given time to satisfy their mobile computing and communication needs. These devices may include, for example, phones and smart phones, laptops, tablets, gaming devices, digital cameras, personal digital assistants, and so on. Personal mobile devices run multiple applications at any given time and run on batteries while their users are mobile. There are various types of batteries available (e.g., lithium polymer batteries, lithium ion batteries, nickel cadmium batteries, etc.) but they all suffer from limited lifetimes. Even though battery technology has improved significantly in the last few years, it is still quite common for users to run down their devices' batteries unexpectedly because of the unpredictable mix of applications they run at any given time.
The battery usage or consumption of a personal mobile device may be monitored with a power management tool. Most power management tools simply monitor a device's battery usage, set off alarms when the battery usage drops below a certain threshold, and display the battery usage for the users to act upon, e.g., by charging the device when needed. Recent tools have been developed to monitor the percentage of battery used by a given component or application running in a device. These tools, however, suffer from significant monitoring overhead and are limited to working in only a small category of devices.
The personal mobile devices of today therefore have a very coarse level of granularity at which battery usage is monitored. Power management tools may monitor battery usage per application but they do not allow users to allocate the battery usage per application. For example, if a user is expecting an important business call at a smart phone that has low battery, the user cannot automatically allocate the battery to the phone call and suspend other applications from draining the battery. Users have to resort to ad-hoc methods based on experience and rudimentary monitoring to turn off applications that are perceived to consume more battery. Further, there is no way for a user to manage or coordinate total available battery power across multiple personal mobile devices.
In addition, a single mobile device is used in multiple contexts (e.g., work, personal, guest, etc.) by a user. These contexts can be considered as multiple user personas that may impose different requirements on the device usage policies, including those related to the battery. A particular persona, say the work persona, may put a higher priority to the e-mail and phone usage, while the guest persona may put a higher priority on some game applications.